My reason for getting into this was to determine the percent above the league average for various rates, in this case, the simple, innocuous, venerable batting average. In 1954 Mays led the NL with .345; Aaron in his rookie season batted .280.

Willie Mays and Hank Aaron have very different lgBA in baseball-reference.com under Advanced Batting. Presumably this is caused by they're having different home parks. Mays had the advantage every season 1954 through 1967 except 1963, which was about even. Aaron's Braves moved from Milwaukee to Atlanta in 1966. Aaron had the advantage every season 1969 through 1973 except 1968 was about even.

The biggest difference for either player was for Aaron 1972 and 1973 when Mays played mostly for the Mets whose home park was Shea Stadium: 13 and 12 points. Mays topped out with a nine point edge in 1957, his Giants last season in New York where they played at the Polo Grounds.

This only matters for something like the simple thing I was trying to do: figure the percent above the league average, which is becoming an increasingly elusive concept.

For Derek Jeter read Yankees. As mentioned in recent posts: "baseball-reference.com definition of lgBA: a league average (non-pitcher) would have had in the same park(s)."

baseball-reference.com has Advanced Batting under "More Stats", which include the season lgBA, league BA. I had noticed significant differences between the lgBA for common seasons for Willie Mays and Hank Aaron.

I decided to select an American League (Conference since 1994) batter because pitchers do not bat and compare his lgBA to the league BA as defined as Hits/AB (at bats). Here is the link with the traditional BA:

baseball-reference.com definition of lgBA: a league average (non-pitcher) would have had in the same park(s).

lgBA of Mays and Aaron differs for common National League seasons: 1954-1973. lgBA appears to be by team, not player. Have requested clarification from baseball-reference.com. Mays split 1972 between two teams and the total lgBA assigned to Mays appears to be a weighted number between the two teams based on at bats for Mays with each team.

Wednesday, May 29, 2013

baseball-reference.com definition: a league average (non-pitcher) would have had in the same park(s).

lgBA of Mays and Aaron differs for common National League seasons: 1954-1973. I found this very surprising, something not mentioned when players are compared, much less the percent above lgBA. It's almost always BA v. BA, even for different eras. In a future post I will plot the respective seasons for percent above lgBA for all three.

Tuesday, May 28, 2013

Data is for the American League (AL) and the National League (NL) 1903-2010, minimum 300 At Bats (AB).There were 192 seasons that met the criteria, including eleven of twelve .400 BA; Bill Terry's .401 in 1931 did not: (.401-.303)/.303 = 32.3%...Twelve were at least 50% higher the league Batting Average (BA). Ten of the twelve were between 1904-1918. (seven by Ty Cobb)

31 players did this more than once (led by Cobb: 14)

Ty Cobb had 7.14% of the seasons.__________________________Rogers Hornsby's .403 in 1925 was the only .400 BA less than 40% above league: 38.2%.

Mickey Mantle's batting average (BA) dropped from .365 in 1957 to .237 in 1968. The previous post addressed the percent above league average, defined in baseball-reference.com as "a league average (non-pitcher) would have had in the same park(s)" for Mantle, Willie Mays and Hank Aaron for BA, OBA, SLG, OPS.

I wondered if baseball-reference.com simply listed an unweighted average for lgBA for a player's seasons of if the lgBA was weighted by the proportion of at bats (AB) or plate appearances (PA) of that player's career. I checked it for Mantle and at least for the lgBA for his seasons, 1951-1968, the lgBA is either weighted or coincidentally correct: .256. Mantle's career BA was .298, 16.41% above lgBA.

OPS road and home ranks are shown and percent difference between road and home OPS. Only these batters had lower OPS home than road:Lou Gehrig -4.17%
DiMaggio -7.59%Ty Cobb - 3.63%Mike Piazza -8.33%

The new baseball-reference.com "play index" platoon slits starts in 1916 for some reason so data for Cobb and Tris Speaker is not complete. Cobb started in 1905, Speaker 1907.

The batters are being compared to themselves. I'm guessing that the home advantage is primarily due to the ball park and the absurd baseball non uniform playing areas, which combined with baseball's non-symmetrical and/or asymmetrical advantage for left handed batters, makes it less fair and more un-American than either football or basketball.

Babe Ruth is number one, both home and road. Further highlighting the one advantage that Mutt Mantle provided to his son Mickey by forcing Mickey to switch hit is avoiding the fate of the great Joe DiMaggio whose ranks are 6/46 and OPS percent difference -7.59%, second biggest deficit to Mike Piazza's -8.33%.

The bottom four were among the home OPS leaders but were so low in road OPS that I didn't bother to get their ranks. For me this pretty much demolishes any Hall of Fame talk about Larry Walker and Todd Helton, both tainted by the altitude friendly park in Colorado with home OPS percent advantages of 23%. Walker played 10 of 17 seasons in Colorado, Helton all 17.

Friday, May 24, 2013

Ruth is number one both home and road. Sixty batters met the criteria compared with 24 in the previous post for road OPS (On Base Plus Slugging averages). OPStot is career. 18 batters >= 1.000 compared with six for road OPS.

For cumulative seasons, From 1916 to 2012, Home (within Home or Away), (requiring onbase_plus_slugging≥.920 and PA≥3000), sorted by greatest On-Base Plus Slugging for this split